The Longitude approach applied to literature: like Dava Sobel's clock-maker, James Boswell was a cash-strapped 18th-century provincial, mocked by the establishment as he devoted years to a groundbreaking project. The history of the composition of the Life of Johnson is itself an epic tale, with Boswell somehow inventing modern biography despite penury, depression, bereavement, humiliating rebuffs by potential patrons and regular bouts of boozing and whoring. Sisman traces the seven-year process brilliantly, and - as the author of an admired life of AJP Taylor - offers a fellow-biographer's perspective on a masterpiece modelled on Dutch painting.

The Prime Minister Peter Hennessy (Penguin, £9.99)

Assessing the 11 occupants of No. 10 since 1945 in turn, Hennessy ends with "Premier League" rankings, with Thatcher and Attlee ("weather-makers") at the top, Eden and Major at the bottom, and Blair provisionally placed mid-table with Heath. He is preoccupied with each PM's reshaping of Whitehall and attitude to Cabinet; many will skip these sections in favour of the superb, gossipy mini-biographies. But it's that odd mixture of dry bureaucratic process and quirky humanity that makes this vast book a kind of Moby-Dick of political history: obsessive, systematic, majestic, but also full of donnish humour and a sense of fun.

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